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Lollipop Plot: Meta-analysis of Gender D...

When I went to the APS conference in San Francisco last year, I got to hear Janet Hyde talk about the gender similarities hypothesis. Broadly, she argues that most gender differences (i.e., men vs. women) in psychological variables tend to be small in size. She used meta-analysis — statistically summarizing the results of lots of published research — as a method of testing her hypothesis. I thought it was fascinating stuff and a great talk, so I wanted to incorporate some of her research into intro psychology. Since I’ve been sprucing up the intro psych...
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Open Sex Role Inventory

Did you know about the Open Source Psychometrics project? It has more than two dozen personality tests that are all free to use with a creative commons license and posts large, open access datasets for their validation? Wow. What’s even stranger is that this site has no university affiliation, so far as I can tell and I can’t find any info on the site’s administrator. They’ve collected data from ~300,000 people here, these datasets are massive and an incredible resource, but are also virtually untouched by the academy. It’s downright...
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Pathfinder Monster Database: AC vs Touch...

Ok, one more visit to this pathfinder monster database before I’m on to a new dataset. This time, I wanted to take a look at the relationship between Armor Class (i.e., how hard a monster is to hit) and Challenge Rating (i.e., how tough the monster is, according to the game developers). There should be a pretty strong linear relationship between AC and CR. However, the thing I’m really interested in is the relationship between Touch AC and CR. Because pathfinder is needlessly complicated, monsters have a separate AC for just touching them (or getting hit with...
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Pathfinder Monster Database Plots

I want to incorporate more R into my classes at Dalhousie. Problem is, I am a pretty bad R coder– I spent much of the past decade or so with SPSS and Mplus. But there’s lots of evidence that R is the future of science. I find that the best way to learn is project-based, so I’m going to start blogging on R code. I’m going to focus on topics that are inherently interesting to me, with a focus on data visualization. If I keep it fun, I’m more likely to stick with it. So, to start I’m going to analyze data from the Pathfinder Monster...
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Generalized Linear Models for Between Su...

There aren’t many good, easy-to-understand resources on Generalized Linear Models. This is a shame, because they are usually a substantial improvement over more conventional ANOVA analyses, because they can much better account for violations of the normality assumption. Check out some tutorial slides I created here: They only cover between-subjects designs. Maybe some time I’ll also make one for generalized mixed models, which take the best of GLiM and multilevel models and combine them into...
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Simple Validity Statistics for Teachers

My primary area of interest (besides statistics) is personality psychology. If there’s one thing you’ll notice about personality psychologists, it’s that we’re kind of obsessed with questionnaire measurement – and usually rely on some pretty complicated statistics to really be satisfied that a questionnaire is suitable for our purposes. Really though, we’re usually interested in two things: Are the questionnaires reliable? That is, does the questionnaire produce consistent results under similar conditions? Are the measurements valid? That is, does the questionnaire...
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Basics of SEM Tutorial

Attached are some slides that I’ve used to teach my PSYO 6003 Multivariate Statistics students the basics of structural equation modelling, which may be of some use to people using it for the first time. Check them out here:
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Multicolinearity: Why you should care an...

Multicolinearity: Why you should care and what to do about it Multicolinearity is a problem for statistical analyses. This large, unwieldy word essentially refers to situations where your predictor variables so highly correlated with one another, they become redundant. Generally speaking, this is a problem because it will increase your Type II error rate (i.e., false negatives). In the most severe cases, multicolinearity can produce really bizarre results that defy logic. For example, the direction of relationships can sometimes reverse (e.g., a positive relationship...